A current trend in the design of electrical systems is the provision of modular configurations whereby the individual electrical devices making up the system are removable from the system housing. Such systems provide a number of advantages. The customer is able to buy a system which has a combination of different device types tailored to his own requirements. In addition, the manufacturer is able to offer a large number of different systems based on a smaller range of individual device types. If a device becomes defective, it can be removed for repair and replaced with a good device without seriously degrading the performance of the system as a whole.
One type of multi component system is a mass data storage subsystem which comprises removable data storage devices, e.g. disk drives, mounted in a chassis which also contains associated device controllers, power supplies and cooling fans.
With removable disk drives, extra provision in the form of improved shock mounts is commonly required to provide protection for the head disk assembly during handling. Although it may be possible to provide protection sufficient to cope with most handling conditions, it is extremely difficult to achieve such a level of protection within the limited space of a fixed form factor e.g. 5.25 inches. Care is also needed when inserting or removing the disk drive into or from the chassis in order to avoid damage to the head disk assembly.
An article entitled `Removable and Transportable DASD` (IBM Technical Disclosure Bulletin vol. 33 No. 6B November 1990 pp 76-77) describes a disk file module which is designed to be removably installed in the chassis of a user system. The module includes a first handle on its front surface for use in removing the module from either rack or tower mounting chassis. A second handle which folds flat at the top of the unit may be used an additional carrying aid.
A similar arrangement is employed in the EMR removable disk subsystem manufactured by Emulex Corporation. A pair of removable Portable Disk Modules (PDM) are mounted in a chassis and each module has a front mounted handle and a second handle hingeably attached to its top surface. The second handle is presumably used to assist in removal of the module from the chassis.